Among compounds which are used as raw materials for synthesizing chemical products, those which are a gas at ordinary temperature and atmospheric pressure, a boiling point thereof being, however, not so low, and can be easily liquefied through pressurization or cooling, are generally handled as a so-called liquefied gas in a state of liquid in a storage container, a transportation container, or the like. In particular, in the case where the liquefied gas is a combustible liquefied gas having combustibility, in order to inhibit explosion or combustion, it is necessary to strictly control the liquefied gas such that the storage container, the transportation container, or the like does not become high in temperature; and that oxygen is not incorporated, or the combustible liquefied gas does not leak out to the outside.
In the case of producing a chemical product through a gas phase oxidation reaction using the combustible liquefied gas as a raw material, in general, the combustible liquefied gas is subjected to solution sending from the storage container or the like to an evaporation apparatus or the like; the combustible liquefied gas is vaporized in the evaporation apparatus or the like; and subsequently, the vaporized combustible liquefied gas is transferred into a reactor, etc. for achieving a gas phase oxidation reaction, to produce a chemical product.
In the conventional art, in the evaporation apparatus or the like, it is performed to vaporize the combustible liquefied gas with a liquid heat transfer medium and recover, as a cold heat, a latent heat to be consumed on the vaporization, and utilize the latent heat for a heat transfer medium for cooling.
For example, Non-Patent Literature 1 describes that liquefied propylene and liquefied ammonia that are raw materials for producing acrylonitrile are vaporized with a glycol aqueous solution, and the glycol aqueous solution after heat exchange is used as a medium for cooling of a refrigeration machine.
Patent Literature 1 discloses a method in which liquefied propylene which is a raw material for producing acrylic acid is vaporized with a liquid heat transfer medium of 0° C. to 50° C., and the liquid heat transfer medium having been cooled with a latent heat required for the vaporization is used for a heat transfer medium for cooling of a heat exchanger of an auxiliary cooler of an acrylic acid collection column or an acrylic acid separation column.